19 research outputs found
Serum levels of glucose and urea blood in suckling calves of the Pantaneira breed fed with Moringa oleifera.
Renormalization Group Theory for a Perturbed KdV Equation
We show that renormalization group(RG) theory can be used to give an analytic
description of the evolution of a perturbed KdV equation. The equations
describing the deformation of its shape as the effect of perturbation are RG
equations. The RG approach may be simpler than inverse scattering theory(IST)
and another approaches, because it dose not rely on any knowledge of IST and it
is very concise and easy to understand. To the best of our knowledge, this is
the first time that RG has been used in this way for the perturbed soliton
dynamics.Comment: 4 pages, no figure, revte
Electron-Electron Interactions and the Hall-Insulator
Using the Kubo formula, we show explicitly that a non-interacting electron
system can not behave like a Hall-insulator, {\it ie.,} a DC resistivity matrix
and finite in the zero temperature
limit, as has been observed recently in experiment. For a strongly interacting
electron system in a magnetic field, we illustrate, by constructing a specific
form of correlations between mobile and localized electrons, that the Hall
resistivity can approximately equal to its classical value. A Hall-insulator is
realized in this model when the density of mobile electrons becomes vanishingly
small. It is shown that in non-interacting electron systems, the
zero-temperature frequency-dependent conductacnce generally does not give the
DC conductance.Comment: 11 pages, RevTeX3.
Grain boundary pinning and glassy dynamics in stripe phases
We study numerically and analytically the coarsening of stripe phases in two
spatial dimensions, and show that transient configurations do not achieve long
ranged orientational order but rather evolve into glassy configurations with
very slow dynamics. In the absence of thermal fluctuations, defects such as
grain boundaries become pinned in an effective periodic potential that is
induced by the underlying periodicity of the stripe pattern itself. Pinning
arises without quenched disorder from the non-adiabatic coupling between the
slowly varying envelope of the order parameter around a defect, and its fast
variation over the stripe wavelength. The characteristic size of ordered
domains asymptotes to a finite value $R_g \sim \lambda_0\
\epsilon^{-1/2}\exp(|a|/\sqrt{\epsilon})\epsilon\ll 1\lambda_0a$ a constant of order unity. Random fluctuations allow defect motion to
resume until a new characteristic scale is reached, function of the intensity
of the fluctuations. We finally discuss the relationship between defect pinning
and the coarsening laws obtained in the intermediate time regime.Comment: 17 pages, 8 figures. Corrected version with one new figur
Dynamics of heteropolymers in dilute solution: effective equation of motion and relaxation spectrum
The dynamics of a heteropolymer chain in solution is studied in the limit of
long chain length. Using functional integral representation we derive an
effective equation of motion, in which the heterogeneity of the chain manifests
itself as a time-dependent excluded volume effect. At the mean field level, the
heteropolymer chain is therefore dynamically equivalent to a homopolymer chain
with both time-independent and time-dependent excluded volume effects. The
perturbed relaxation spectrum is also calculated. We find that heterogeneity
also renormalizes the relaxation spectrum. However, we find, to the lowest
order in heterogeneity, that the relaxation spectrum does not exhibit any
dynamic freezing, at the point when static (equilibrium) ``freezing''
transition occurs in heteropolymer. Namely, the breaking of
fluctuation-dissipation theorem (FDT) proposed for spin glass dynamics does not
have dynamic effect in heteropolymer, as far as relaxation spectrum is
concerned. The implication of this result is discussed
Measurement and Study of Electromagnetic Emission Generated by Tensile Fracture of Polymers and Carbon Fibres
De novo assembly of a transcriptome from the eggs and early embryos of Astropecten aranciacus
Starfish have been instrumental in many fields of biological and ecological research. Oocytes of Astropecten aranciacus, a common species native to the Mediterranean Sea and the East Atlantic, have long been used as an experimental model to study meiotic maturation, fertilization, intracellular Ca2+ signaling, and cell cycle controls. However, investigation of the underlying molecular mechanisms has often been hampered by the overall lack of DNA or protein sequences for the species. In this study, we have assembled a transcriptome for this species from the oocytes, eggs, zygotes, and early embryos, which are known to have the highest RNA sequence complexity. Annotation of the transcriptome identified over 32,000 transcripts including the ones that encode 13 distinct cyclins and as many cyclin-dependent kinases (CDK), as well as the expected components of intracellular Ca2+ signaling toolkit. Although the mRNAs of cyclin and CDK families did not undergo significant abundance changes through the stages from oocyte to early embryo, as judged by real-time PCR, the transcript encoding Mos, a negative regulator of mitotic cell cycle, was drastically reduced during the period of rapid cleavages. Molecular phylogenetic analysis using the homologous amino acid sequences of cytochrome oxidase subunit I from A. aranciacus and 30 other starfish species indicated that Paxillosida, to which A. aranciacus belongs, is not likely to be the most basal order in Asteroidea. Taken together, the first transcriptome we assembled in this species is expected to enable us to perform comparative studies and to design gene-specific molecular tools with which to tackle long-standing biological questions